Display device and personal immersive system and mobile terminal system using the same

ABSTRACT

In a display device and a personal immersive system and a mobile terminal system using the same, at least a part of the display panel includes a switch element configured to electrically connect adjacent sub-pixels to each other in response to a first logic value of a control signal, and electrically separate the adjacent sub-pixels from each other in response to a second logic value of the control signal, a display driver applies the second logic value of the control signal to the switch element when receiving pixel data to be written to a focal region on the display panel to which a user&#39;s gaze is directed, and applies the first logic value of the control signal to the switch element when receiving pixel data to be written to a non-focal region on the display panel.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority of Korean Patent Application No.10-2021-0068873 filed on May 28, 2021, which is hereby incorporated byreference in its entirety.

BACKGROUND Field of the Disclosure

The present disclosure relates to a display device and a personalimmersive system and a mobile terminal system using the same.

Description of the Background

Virtual reality technology is developing the fastest in defense,architecture, tourism, film, multimedia, and game fields. Virtualreality refers to a specific environment or situation that feels similarto the real environment using stereoscopic image technology.

Personal immersive devices have been developed in various forms, such asa head mounted display (HMD), a face mounted display (FMD), and aneyeglasses-type display (EGD). The personal immersive devices aredivided into a virtual reality (VR) device and an augmented reality (AR)device.

Although there have been various studies on reducing power consumptionin the personal immersive devices without degrading perceived imagequality, the power consumption could not be reduced to a satisfactorylevel.

SUMMARY

Accordingly, the present disclosure is to solve the aforementioned needsand/or problems.

More specifically, the present disclosure is to provide a personalimmersive system and a mobile terminal system capable of reducing powerconsumption without degrading perceived image quality.

Additional features and advantages of the disclosure will be set forthin the description which follows and in part will be apparent from thedescription, or may be learned by practice of the disclosure. Otheradvantages of the present disclosure will be realized and attained bythe structure particularly pointed out in the written description andclaims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the presentdisclosure, as embodied and broadly described, a display device includea display panel in which a plurality of data lines, a plurality of gatelines, and a plurality of sub-pixels electrically connected to the datalines and the gate lines are arranged; and a display driver configuredto drive the display panel by writing pixel data to the sub-pixels.

At least a part of the display panel includes a switch elementconfigured to electrically connect adjacent sub-pixels to each other inresponse to a first logic value of a control signal, and electricallyseparate the adjacent sub-pixels from each other in response to a secondlogic value of the control signal.

The display driver is configured to apply the second logic value of thecontrol signal to the switch element when receiving pixel data to bewritten to a focal region on the display panel to which a user's gaze isdirected.

The display driver is configured to apply the first logic value of thecontrol signal to the switch element when receiving pixel data to bewritten to a non-focal region other than the focal region on the displaypanel.

In another aspect of the present disclosure, a personal immersive systemincludes a system controller configured to lower resolution of an inputimage in a non-focal region, which is outside a focal region, than inthe focal region to which a user's gaze is directed; and a displaydriver configured to write pixel data of the focal region and pixel dataof the non-focal region to pixels of a display panel, supply a blackgrayscale voltage to at least some of pixels of the non-focal region onthe display panel, and generate a control signal for lowering luminanceof the non-focal region than luminance of the focal region.

In a further aspect of the present disclosure, a mobile terminal systeminclude a system controller configured to lower resolution of an inputimage in a non-focal region, which is outside a focal region, than inthe focal region to which a user's gaze is directed; and a displaydriver configured to write pixel data of the focal region and pixel dataof the non-focal region to pixels of a display panel, supply a blackgrayscale voltage to at least some of pixels of the non-focal region onthe display panel, and generate a control signal for lowering luminanceof the non-focal region than luminance of the focal region.

In each of the personal immersive system and the mobile terminal system,at least a part of a screen of the display panel may include a switchelement configured to connect adjacent sub-pixels to each other inresponse to a first logic value of the control signal and separate theadjacent sub-pixels from each other in response to a second logicalvalue of the control signal.

In the present disclosure, pixels in the non-focal region outside thefocal region to which the user's gaze is directed may be driven in alump using the switch element, and a black grayscale voltage may beapplied to some of the pixels in the non-focal region, thereby loweringthe luminance of the non-focal region that does not perceived by theuser to reduce power consumption without degrading image quality. Sincethe focal region is reproduced in high resolution on the display panel,there is little deterioration in image quality perceived by the user.

In the present disclosure, power consumption and electromagneticinterference (EMI) may be reduced by lowering the amount of pixel datatransmitted to a data driver and the number of transitions in thenon-focal region.

Effects of the present disclosure are not limited to those mentionedabove, and other effects not mentioned will be clearly understood bythose skilled in the art from the description of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and advantages of the present disclosure will becomemore apparent to those of ordinary skill in the art by describingexemplary aspects thereof in detail with reference to the attacheddrawings, in which:

FIG. 1 is a block view schematically illustrating a display deviceaccording to an aspect of the present disclosure;

FIG. 2 is a diagram illustrating a focal region on a screen;

FIG. 3 is a flowchart illustrating an operation of a display driver;

FIGS. 4A and 4B are diagrams illustrating a display driver and a displaypanel shown in FIG. 1 in detail;

FIG. 5 is a circuit diagram illustrating an example of a pixel circuit;

FIG. 6 is a diagram illustrating an operation of a display driver in afocal region;

FIG. 7 is an equivalent circuit diagram schematically illustratingoperations of adjacent sub-pixels in a focal region;

FIG. 8 is a diagram illustrating an operation of a display driver in anon-focal region;

FIG. 9 is an equivalent circuit diagram schematically illustratingoperations of adjacent sub-pixels in a non-focal region;

FIGS. 10 and 11 are circuit diagrams illustrating a switch elementconnected to three adjacent sub-pixels;

FIGS. 12 and 13 are circuit diagrams illustrating switch elementsconnected to four adjacent sub-pixels.

FIG. 14 is a diagram illustrating an example in which the luminance of anon-focal region is gradually lowered as the distance from a focalregion increases;

FIG. 15 is a diagram illustrating one pixel line in a non-focal region;

FIG. 16 is a diagram illustrating an input/output signal of a timingcontroller for transmitting data to be written in pixels of one pixelline shown in FIG. 15 ;

FIG. 17 is a diagram illustrating a one pixel line traversing a focalregion and a non-focal region;

FIG. 18 is a diagram illustrating an input/output signal to/from atiming controller for transmitting data to be written in pixels of onepixel line shown in FIG. 17 ;

FIG. 19 is a diagram illustrating a display driver according to anotheraspect of the present disclosure;

FIG. 20 is a circuit diagram illustrating an operation of a data drivershown in FIG. 19 in a focal region; and

FIG. 21 is a circuit diagram illustrating an operation of a data drivershown in FIG. 19 in a non-focal region.

DETAILED DESCRIPTION

The advantages and features of the present disclosure and methods foraccomplishing the same will be more clearly understood from aspectsdescribed below with reference to the accompanying drawings. However,the present disclosure is not limited to the following aspects but maybe implemented in various different forms. Rather, the present aspectswill make the disclosure of the present disclosure complete and allowthose skilled in the art to completely comprehend the scope of thepresent disclosure. The present disclosure is only defined within thescope of the accompanying claims.

The shapes, sizes, ratios, angles, numbers, and the like illustrated inthe accompanying drawings for describing the aspects of the presentdisclosure are merely examples, and the present disclosure is notlimited thereto. Like reference numerals generally denote like elementsthroughout the present disclosure. Further, in describing the presentdisclosure, detailed descriptions of known related technologies may beomitted to avoid unnecessarily obscuring the subject matter of thepresent disclosure.

The terms such as “comprising,” “including,” “having,” and “consist of”used herein are generally intended to allow other components to be addedunless the terms are used with the term “only.” Any references tosingular may include plural unless expressly stated otherwise.

Components are interpreted to include an ordinary error range even ifnot expressly stated.

When the position relation between two components is described using theterms such as “on,” “above,” “below,” and “next,” one or more componentsmay be positioned between the two components unless the terms are usedwith the term “immediately” or “directly.”

The terms “first,” “second,” and the like may be used to distinguishcomponents from each other, but the functions or structures of thecomponents are not limited by ordinal numbers or component names infront of the components.

The same reference numerals may refer to substantially the same elementsthroughout the present disclosure.

The following aspects can be partially or entirely bonded to or combinedwith each other and can be linked and operated in technically variousways. The aspects can be carried out independently of or in associationwith each other.

In the following description, when it is determined that a detaileddescription of a known function or configuration related to the presentdisclosure may unnecessarily obscure the gist of the present disclosure,the detailed description thereof will be omitted.

Hereinafter, various aspects of the present disclosure will be describedin detail with reference to the accompanying drawings.

Referring to FIGS. 1 and 2 , a display device of the present disclosureincludes a display panel 100, a system controller 300, a display driver200, and the like.

The system controller 300 may include a main circuit board of atelevision (TV) system, a computer system, a set-top box, a navigationsystem, a mobile terminal system, a wearable system, or avirtual/augmented reality system (hereinafter referred to as “VR/ARsystem”). Hereinafter, it should be noted that the system controller 300is mainly described based on a virtual reality system, but is notlimited thereto.

The system controller 300 is connected to a sensor 310, a camera 320,and the like. The system controller 300 further includes an externaldevice interface connected to a memory or an external video source, auser interface for receiving a user command, a power supply forgenerating power, and the like. The external device interface, the userinterface, the power supply, and the like are omitted from the drawings.The system controller 300 adjusts the resolution of a focal region and anon-focal region by using a graphic image processing unit such as agraphic processing unit (GPU) that performs image processing of an inputimage. The external device interface may be implemented with variouswell-known interface modules, such as a universal serial bus (USB) and ahigh definition multimedia interface (HDMI).

The system controller 300 transmits pixel data of the input image and atiming signal synchronized thereto to the display driver 200. The systemcontroller 300 analyzes image data from the camera 320 that capturesuser's left and right eyes with a preset eye tracking algorithm toestimate the focal region to which the user's left and right eyes aredirected. The system controller 300 adjusts the resolution of the inputimage in the focal region and the non-focal region outside the focalregion by using a foveated rendering algorithm. The system controller300 converts the pixel data resolution of the input image according tothe resolution of the focal region and the non-focal region by using ascaler.

In the case of the VR/AR system, since the user's eyes are very close toa screen AA of the display panel 100, a high resolution greater than orequal to 4K is required. The foveated rendering algorithm may increasethe resolution of pixel data corresponding to the focal region displayedon the display panel 100 by using the position information of thepupils, and may reduce the amount of transmitted data and the number oftransitions by repeatedly constructing the same data on a predeterminedpixel block basis in the non-focal region other than the focal region.The foveated rendering algorithm may reduce the amount of datatransmitted to the display driver 200 by 80% or more by encoding pixeldata to be written to the pixels of the focal region into arepresentative value.

The system controller 300 may transmit high-resolution data to thedisplay driver 200 by increasing or without lowering the resolution ofthe pixel data to be written to the pixels of the focal region on thedisplay panel 100. In this regard, the system controller 300 maygradually or stepwisely lower the resolution of the pixel data from thecenter of the focal region to the edge thereof. The system controller300 significantly lowers the resolution of the non-focal region toreduce the data transmission amount and the number of transitions.

In the VR/AR system, due to the intrinsic characteristics of the opticnerve, the user can only perceive a low-resolution image reproduced inthe pixels of the non-focal region other than the focal region. Aresolution compression range that will not degrade perceived imagequality while lowering the data transmission amount may be set as shownin FIG. 2 .

In the VR system, the focal region may be set to a size having adiameter of 2.8 mm in consideration of the distance between the user'spupils and the screen AA. The focal region may be divided into N (Nbeing a positive integer greater than or equal to 2) regions from thecenter to the edge. In the case where the focal region is divided intothree regions having different resolutions, if the pixel data resolutionof a first region FR1 corresponding to the center of the focal region is100%, the pixel data resolution of a second region FR2 outside the firstregion FR1 may be reduced to 25%, and the pixel data resolution of athird region FR3 outside the second region FR2 may be reduced to 11.1%.The resolution of a non-focal region NFR may be 6.2%. The diameter ofthe first region FR1 may be set to 1.2 mm, the diameter of the secondregion FR2 may be set to 1.9 mm, and the diameter of the third regionFR3 may be set to 2.8 mm, but they are not limited thereto. In the VRsystem, the focal region may be approximately 2% of the entire screenAA.

The sensor 310 includes various sensors such as a gyro sensor and anacceleration sensor. The sensor 310 transmits the outputs of the varioussensors to the system controller 300. The system controller 300 mayreceive the output of the sensor 310 and move the pixel data of theimage displayed on the screen AA in synchronization with the user'smovement. Accordingly, the position of the focal region on the screen AAmay be changed in synchronization with the movement of the user's pupilsand head.

As shown in FIG. 3 , when receiving the pixel data of the input imagefrom the system controller 300 through an interface receiving circuit(step S1), the display driver 200 writes the pixel data into the pixelsof the display panel 100. The display driver 200 may lower the luminanceof the pixel data written to the pixels of the non-focal region toreduce power consumption.

The display driver 200 writes high-resolution pixel data into the pixelsof the focal region on the screen AA of the display panel 100 (steps S2and S3). The resolution of the pixel data within the focal region may begradually or stepwisely lowered from the center to the edge. On theother hand, the display driver 200 writes low-resolution pixel data intothe pixels of the non-focal region outside the focal region, and lowersthe luminance of the non-focal region than that of the focal region(steps S2 and S4).

FIGS. 4A and 4B are diagrams illustrating the display driver and thedisplay panel shown in FIG. 1 in detail.

Referring to FIG. 4A, the display device of the present disclosureincludes a first display panel 100A, a second display panel 100B, andthe display driver for driving the first and second display panels 100Aand 100B.

The first and second display panels 100A and 100B may be implemented asdisplay panels for displaying images in a flat panel display device suchas a liquid crystal display (LCD) device or an electroluminescencedisplay device. The electroluminescent display device may be classifiedinto an inorganic light emitting display device and an organic lightemitting display device according to the material of a light emittinglayer. As an example of the inorganic light emitting display device,there is a quantum dot display device. Hereinafter, the display devicewill be mainly described as the organic light emitting display device,but is not limited thereto.

The first display panel 100A may be a display panel for the left eye,and the second display panel 100B may be a display panel for the righteye, but they are not limited thereto. In the case of a mobile terminalsystem such as a smartphone, a left-eye image and a right-eye image maybe displayed together on the screen AA of one display panel 100 shown inFIG. 4B. In the case of a smartphone, a VR mode is supported as anexample of a partial mode. In the VR mode of the smartphone, theleft-eye image and the right-eye image may be displayed separately onone display panel. In the mobile terminal system according to thepresent disclosure, the left-eye image and the right-eye image may bedisplayed on one display panel in the VR mode, and the luminance of animage displayed in the non-focal region outside the high-resolutionfocal region may be controlled to be lower than that in the focal regionin each of the left-eye image and the right-eye image.

Each of the display panels 100A and 100B includes data lines to whichthe pixel data of the input image is applied, gate lines (or scan lines)to which a gate signal is applied, and pixels arranged in a matrix formby a cross structure of the data lines and the gate lines. An image isdisplayed on pixel arrays disposed on the screens AA of the displaypanels 100A and 100B.

Each of the pixels may be divided into sub-pixels 101 such as a redsub-pixel, a green sub-pixel, and a blue sub-pixel to reproduce color.Each of the pixels may further include a white sub-pixel. In the case ofthe organic light emitting display device, each of the sub-pixels 101may include a pixel circuit shown in FIG. 5 , but is not limitedthereto.

In a personal immersive system such as the VR/AR system, the left-eyeimage having lower luminance in the non-focal region than in the focalregion may be displayed on the first display panel 100A. The right-eyeimage having lower luminance in the non-focal region than in the focalregion may be displayed on the second display panel 100B.

In FIG. 4A, pixel lines L1, L2, . . . , Ln include one line of pixels towhich pixel data is simultaneously written for one horizontal period onthe screens of the display panels 100A and 100B. When the resolution ofthe screen AA is m*n, the screen AA includes n pixel lines L1, L2, . . ., Ln. In the display panel 100 of FIG. 4B, data is simultaneouslywritten to pixels P of one of the pixel lines.

The display driver 200 writes the data of the input image to the displaypanels 100A and 100B. The display driver 200 includes data drivers 111and 112, gate drivers 121 and 122, a timing controller 130, and thelike.

A first data driver 111 and a first gate driver 121 are connected to thefirst display panel 100A to drive the first display panel 100A under thecontrol of the timing controller 130. A second data driver 112 and asecond gate driver 122 are connected to the second display panel 100B todrive the second display panel 100B under the control of the timingcontroller 130.

In the case of a mobile terminal system, as shown in FIG. 4B, the datadriver and the timing controller may be built in a drive IC D-IC.

The data drivers 111 and 112 convert the pixel data from the timingcontroller 130 into a data voltage using a gamma compensation voltage,and output the data voltage to data lines 102. The data drivers 111 and112 convert black grayscale data set separately from the pixel data ofthe input image into a black grayscale voltage using the gammacompensation voltage under the control of the timing controller 130, andmay output the black grayscale voltage to the data lines 102.Accordingly, the pixel data voltage or the black grayscale voltage maybe applied to each of the sub-pixels 101 through the data lines 102.

The gate drivers 121 and 122 output a gate signal (or scan signal)synchronized with the pixel data to gate lines 104. The gate drivers 121and 122 include shift registers for sequentially supplying the gatesignal to gate lines G1 to Gn by shifting the pulse of the gate signal.

The timing controller 130 transmits the pixel data of the input imagereceived from the system controller 300 to the data drivers 111 and 112.The timing controller 130 may transmit the black grayscale data togetherwith the pixel data to the data drivers 111 and 112. The timingcontroller 130 receives timing signals synchronized with the pixel dataof the input image from the system controller 300, and controls theoperation timings of the data drivers 111 and 112 and the gate drivers121 and 122 based on the timing signals.

The timing controller 130 may count the pixel data of the input image asa clock to determine the positions of pixels into which the pixel datais written. The timing controller 130 transmits a control signal forcontrolling the pixel luminance of the focal region and the non-focalregion to the data drivers 111 and 112, and if the pixel data of theinput image is to be written into pixels belonging to the non-focalregion, activates the control signal for lowering the pixel luminance tocontrol the pixel luminance of the non-focal region to be lower thanthat of the focal region.

In FIG. 4B, the drive IC D-IC may be electrically connected to thesystem controller 300 through flexible printed circuits (FPC), and maybe electrically connected to a gate driver 120 and the data lines 102 onthe display panel 100. The drive IC D-IC includes the data driver andthe timing controller. Accordingly, the drive IC D-IC converts the pixeldata received from the system controller 300 into a data voltage tosupply it to the data lines 102, and controls the operation timing ofthe gate driver 120. The drive IC D-IC generates a control signal forlowering the luminance of the pixels P in the non-focal region, so thatthe luminance of the pixels P in the non-focal region is lowered inresponse to the control signal.

In a mobile terminal system such as a smartphone, the left-eye image inwhich the luminance of the non-focal region is lower than that of thefocal region, and the right-eye image in which the luminance of thenon-focal region is lower than that of the focal region may be displayedon one display panel 100.

Each of the sub-pixels 101 includes a pixel circuit for driving a lightemitting element OLED. The pixel circuit is not limited to that shown inFIG. 5 .

Referring to FIG. 5 , the pixel circuit includes the light emittingelement OLED, a driving element DT for supplying a current to the lightemitting element OLED, a switch element M01 that connects the data line102 to the driving element DT in response to a scan pulse SCAN, and acapacitor Cst connected to the gate of the driving element DT. Each ofthe driving element DT and the switch element M01 may be implementedwith a transistor.

A pixel driving voltage VDD is applied to a first electrode of thedriving element DT through a power line 103. The switch element M01 isturned on in response to the gate-on voltage of the gate signal SCAN tosupply a data voltage Vdata to the gate electrode of the driving elementDT and the capacitor Cst. The driving element DT supplies a current tothe light emitting element OLED according to a gate-source voltage Vgsto drive the light emitting element OLED.

The anode electrode of the light emitting element OLED is connected to asecond electrode of the driving element DT, and the cathode electrodethereof is connected to a low potential voltage source VSS. When aforward voltage between the anode electrode and the cathode electrode isequal to or greater than a threshold voltage, the light emitting elementOLED is turned on to emit light. The capacitor Cst is connected betweenthe gate electrode and the source electrode of the driving element DT tomaintain the gate-source voltage Vgs of the driving element DT.

As shown in FIGS. 7 and 9 , adjacent sub-pixels may be connected througha switch element SW in at least a part of the screen AA. When pixel datais written to a sub-pixel of the focal region and black grayscale datais written to a sub-pixel adjacent thereto, if the sub-pixels areshort-circuited through the switch element SW, a current I_(OLED) of thelight emitting element OLED is discharged through the adjacentsub-pixels, thereby lowering the luminance of the pixel data. The switchelement SW may be implemented with a transistor.

The display driver 200 may write pixel data to any one of n (n being apositive integer greater than or equal to 2) sub-pixels adjacent to eachother within the non-focal region, and may write black grayscale datathat is preset to the other sub-pixels. In particular, as shown in FIGS.8 and 9 , when pixel data to be written into the sub-pixels of thenon-focal region is received, the timing controller 130 may apply acontrol signal BREN of an activation logic value for controlling on/offof the switch element SW to a control electrode (or gate electrode) ofthe switch element SW to turn on the switch element SW, therebycontrolling the luminance of the non-focal region to be lower than thatof the focal region.

FIG. 6 is a diagram illustrating an operation of a display driver in afocal region. FIG. 7 is an equivalent circuit diagram schematicallyillustrating operations of adjacent sub-pixels in a focal region.

Referring to FIGS. 6 and 7 , the timing controller 130 receives pixeldata DATA of an input image from the system controller 300 through aninterface receiving circuit. As described above, the pixel data DATA ofthe non-focal region has a lower resolution than the pixel data DATA ofthe focal region.

The interface receiving circuit may encode N (N being a positive integergreater than or equal to 2) pixel data into one data packet and transmitit to the timing controller 130. A decoder in the timing controller 130may decode each data packet received and sequentially transmit N pixeldata to a data driver 110.

The timing controller 130 includes a control signal output terminal 130a. The data driver 110 includes a control signal input terminal 110 aand an output terminal 110 b. The data driver 110 converts pixel data Dreceived from the timing controller 130 into the data voltage Vdata andsupplies it to the data lines 102.

Adjacent sub-pixels SP1 and SP2 are connected to each other through theswitch element SW in at least a part of the screen AA. The switchelement SW may be connected between the anode electrodes of the lightemitting elements OLED formed in the adjacent sub-pixels SP1 and SP2,but is not limited thereto.

When the pixel data of the focal region is received, the timingcontroller 130 outputs the control signal BREN as an inactivation logicvalue, e.g., a logic value of 0 (or low). As a result, the switchelement SW connected between the adjacent sub-pixels SP1 and SP2 in thefocal region is turned off, so that the sub-pixels SP1 and SP2 areelectrically separated from each other. In this case, the data voltageVdata of the pixel data is independently charged in each of thesub-pixels SP1 and SP2. Accordingly, the current I_(OLED) flows throughthe light emitting element OLED in each of the sub-pixels SP1 and SP2 ofthe focal region, and the light emitting element OLED emits light with abrightness corresponding to the grayscale of the pixel data.

FIG. 8 is a diagram illustrating an operation of a display driver in anon-focal region. FIG. 9 is an equivalent circuit diagram schematicallyillustrating operations of adjacent sub-pixels in a non-focal region.

Referring to FIGS. 8 and 9 , when the pixel data DATA of the non-focalregion is received, the timing controller 130 may transmit blackgrayscale data B stored in the memory together with the pixel data D tothe data driver 110. While the data of the non-focal region is received,the data driver 110 supplies the data voltage Vdata of the pixel data tothe odd-numbered data lines 102 and supplies a black grayscale voltageVblk to the even-numbered data lines 102. Accordingly, the data voltageVdata of the pixel data is applied to one of the adjacent sub-pixels SP1and SP2 in the non-focal region, while the black grayscale voltage Vblkis applied to the other one. In the case of the sub-pixel to which theblack grayscale voltage Vblk is applied, the driving element DT of thesub-pixel is not turned on, but a current may flow through the lightemitting element OLED due to a current applied from its adjacentsub-pixel through the switch element SW, so that the light emittingelement OLED may emit light with low brightness. If the black grayscalevoltage Vblk is applied to all of the sub-pixels connected through theswitch element SW, a current does not flow through the light emittingelement OLED in the sub-pixels, so that the sub-pixels do not emitlight.

When the pixel data of the non-focal region is received, the timingcontroller 130 outputs the control signal BREN as an activation logicvalue, e.g., a logic value of 1 (or high). As a result, the switchelement SW connected between the adjacent sub-pixels SP1 and SP2 in thenon-focal region is turned on. When the switch element SW is turned on,the anode electrodes of the light emitting elements OLED formed in theadjacent sub-pixels SP1 and SP2 are short-circuited.

When the sub-pixels SP1 and SP2 are short-circuited through the switchelement SW, the data voltage Vdata of the pixel data is charged in thefirst sub-pixel SP1, while the black grayscale voltage Vblk is appliedto the second sub-pixel SP2. As a result, the current I_(OLED) flowingthrough the light emitting element OLED of the first sub-pixel SP1 flowsthrough two light emitting elements OLED formed in the adjacentsub-pixels SP1 and SP2.

If it is assumed that the light emitting elements OLED formed in theadjacent sub-pixels SP1 and SP2 have the same electrical characteristicswhen the switch element SW is turned on, since the impedance of the twolight emitting elements OLED is the same, the current I_(OLED) flowsthrough both the light emitting elements OLED by half. As a result, theamount of current flowing through the light emitting elements OLED inthe adjacent sub-pixels SP1 and SP2 connected through the switch elementSW is reduced to about ½ (I_(OLED)/2) level.

When the adjacent sub-pixels SP1 and SP2 in the non-focal region areshort-circuited through the switch element SW, even if pixel data of apeak white grayscale (or the highest grayscale) is applied to thesub-pixels of the focal region and the non-focal region, the luminanceof the sub-pixels located in the non-focal region becomes lower than theluminance of the sub-pixels located in the focal region. Accordingly, inthe present disclosure, power consumption may be significantly reducedby lowering the luminance in the non-focal region where the user doesnot perceive the image quality degradation.

The switch element for lowering the luminance of the sub-pixels in thenon-focal region may connect a plurality of adjacent sub-pixels to eachother as shown in FIGS. 10 to 13 . By using these sub-pixels, theluminance of the pixels in the non-focal region may be gradually loweredas the distance from the focal region increases. For example, as shownin FIG. 14 , the non-focal region NFR may be divided into a firstnon-focal region NFR1 that is close to the focal region FR and a secondnon-focal region NFR2 that is relatively far from the focal region FR.The first non-focal region NFR1 is a pixel area between the focal regionFR and the second non-focal region NFR2.

The first non-focal region NFR1 may include the sub-pixels SP1 and SP2shown in FIGS. 7 and 9 . The second non-focal region NFR2 may includesub-pixels SP1 to SP4 shown in FIGS. 10 to 13 .

In an aspect shown in FIGS. 10 and 11 , three sub-pixels are connectedto each other through switch elements SW, and as shown in FIG. 11 , whenthe switch elements SW are turned on, the amount of current flowingthrough the light emitting elements OLED of the sub-pixels may bereduced to about ⅓ (I_(OLED)/3). In an aspect shown in FIGS. 12 and 13 ,four sub-pixels are connected to each other through switch elements SW,and as shown in FIG. 13 , when the switch elements SW are turned on, theamount of current flowing through the light emitting elements OLED ofthe sub-pixels may be reduced to about ¼ (I_(OLED)/4). Accordingly, asthe number of sub-pixels connected through the switch elements SWincreases, the luminance of the non-focal region NFR1 and NFR2 may becontrolled to be lower.

When the pixel data of the same grayscale is applied to all pixels ofthe screen AA, the luminance of the first non-focal region NFR1 may becontrolled to be lower than the luminance of the focal region FR usingthe pixel circuits shown in FIGS. 7 and 9 , and the luminance of thesecond non-focal region NFR2 may be controlled to be lower than theluminance of the first non-focus region NFR1 using the pixel circuitsshown in FIGS. 10 to 13 .

The control signal BREN may be generated with the number of bitscorresponding the number of pixel groups divided in one pixel line. Forexample, when one pixel line is divided into ten pixel groups, thetiming controller 130 may output a 10-bit control signal BREN [9:0] forone horizontal period.

FIG. 15 is a diagram illustrating one pixel line in a non-focal region.FIG. 16 is a diagram illustrating an input/output signal of a timingcontroller for transmitting data to be written into pixels of one pixelline shown in FIG. 15 . In FIG. 16 , “TCON” denotes the timingcontroller 130, “D” is pixel data, and “B” is black grayscale data.“SOP” is a start code assigned to the beginning of the pixel data of onepixel line inputted to the timing controller 130, and “EOP” is an endcode assigned to the end of the pixel data of one pixel line. It isassumed that a first pixel line L1 includes only sub-pixels of thenon-focal region NFR. In this case, the timing controller 130 mayreceive the pixel data of the input image, add black grayscale data tobetween the pixel data to be applied to the first pixel line L1 duringthe first horizontal period, and transmits it to the data driver 110.For example, the timing controller 130 may transmit data decoded into apair of data including the pixel data D and the black grayscale data Bto the data driver 110.

FIG. 17 is a diagram illustrating one pixel line traversing a focalregion and a non-focal region. FIG. 18 is a diagram illustrating aninput/output signal to/from a timing controller for transmitting data tobe written into pixels of one pixel line shown in FIG. 17 .

An i^(th) (i being a positive integer) pixel line Li shown in FIG. 17may exist in the focal region where the user's gaze is directed. Whenthe user's gaze moves, the focal region also moves. The timingcontroller 130 may receive the pixel data of the input image andrearrange, among the pixel data to be applied to the i^(th) pixel lineLi during an i^(th) horizontal period, data to be written to thesub-pixels of the non-focal region NFR into a pair of data decoded intothe pixel data D and the black grayscale data B. Then, the timingcontroller 130 may transmit it to the data driver 110 in synchronizationwith the activation logic value of the control signal BREN. In addition,the timing controller 130 may transmit, among the pixel data to beapplied to the i^(th) pixel line Li, the pixel data D of the sub-pixelsof the focal region FR to the data driver 110 in synchronization withthe inactivation logic value of the control signal BREN.

In FIGS. 16 and 18 , the timing controller 130 receives pixel data DATA0to DATAX and transmits a total of X pixel data to be written into thesub-pixels of one pixel line to the data driver 110 using a decoder. InN_DATA0 to N-DATAX, “8” is the number of repetitions of the same pixeldata. When the decoder receives one pixel data, e.g., DATA0, ittransmits the pixel data by the number defined in the number ofrepetitions. “SOP (Start of Packet)” is a start code of a data packetincluding pixel data of one pixel line, and “EOP (End of Packet)” is anend code of the data packet.

FIG. 19 is a diagram illustrating a display driver according to anotheraspect of the present disclosure.

Referring to FIG. 19 , the timing controller 131 receives the pixel dataof the input image from the system controller 300 through the interfacereceiving circuit. As described above, the pixel data DATA of thenon-focal region NFR has a lower resolution than the pixel data DATA ofthe focal region FR.

The adjacent sub-pixels SP1 and SP2 are connected through the switchelement SW in at least a part of the screen AA. The switch element SW isconnected between the anode electrodes of the light emitting elementsOLED formed in the adjacent sub-pixels SP1 and SP2.

When the pixel data D of the focal region FR is received, the timingcontroller 131 outputs the control signal BREN as the inactivation logicvalue. When the pixel data D of the non-focal region NFR is received,the timing controller 131 outputs the control signal BREN as theactivation logic value.

The data driver 111 receives the pixel data D and the control signalBREN from the timing controller 130. The data driver 111 converts theblack grayscale data B into a black grayscale voltage in response to theactivation logic value of the control signal BREN. The data driver 111does not output the black grayscale voltage when the control signal BRENis the inactivation logic value. In this aspect, the timing controller131 may not output the black grayscale data, and the black grayscalevoltage may be generated in the data driver 111.

In the focal region FR, the switch elements SW connected between theadjacent sub-pixels SP1 and SP2 are turned off to electrically separatethe sub-pixels SP1 and SP2 from each other. In this case, the currentI_(OLED) flows through the light emitting element OLED in each of thesub-pixels SP1 and SP2 of the focal region FR, so that the lightemitting element OLED emits light with a brightness corresponding to thegrayscale of the pixel data.

In the non-focal region NFR, the switch elements SW connected betweenthe adjacent sub-pixels SP1 and SP2 are turned on to distribute thecurrent I_(OLED) to the light emitting elements OLED formed in thesub-pixels SP1 and SP2, so that the luminance of the sub-pixels SP1 toSP4 is lowered.

FIG. 20 is a circuit diagram illustrating an operation of the datadriver 111 shown in FIG. 19 in a focal region.

Referring to FIG. 20 , the data driver 111 includes a plurality of pixeldata channels CH1 and CH3 and a plurality of switchable channels CH2 andCH4.

Each of the pixel data channels CH1 and CH3 converts the pixel data D tobe written to the pixels of the focal region FR and the non-focal regionNFR into the data voltage Vdata and outputs it. When the pixel data D ofthe focal region FR is received, each of the switchable channels CH2 andCH4 converts the pixel data D into the data voltage Vdata to output it,and when the pixel data D of the non-focal region NFR is received,outputs the black grayscale voltage Vblk.

Each of the channels CH1 to CH4 includes a sample & holder connected toa signal transmission unit SR of a shift register, a digital to analogconverter (hereinafter referred to as “DAC”), and an output buffer SA.

The shift register includes signal transmission units SR forsequentially shifting input data. A multiplexer MUX and a firstdemultiplexer DEMUX1 are alternately connected between the signaltransmission units SR. Multiplexers MUX and first demultiplexers DEMUX1are alternately connected between the signal transmission units SR. Forexample, the multiplexer MUX may be connected between an M^(th) (M beinga positive integer) signal transmission unit SR(M) and an (M+1)^(th)signal transmission unit SR(M+1). The first demultiplexer DEMUX1 may beconnected between the (M+1)^(th) signal transmission unit SR(M+1) andan(M+2)^(th) signal transmission unit SR(M+2). When the multiplexer MUXis connected to the input terminal of the signal transmission unit SR,the first demultiplexer DEMUX1 is connected to the output terminal ofthe signal transmission unit SR. In addition, the first demultiplexerDEMUX1 is connected to the input terminal of a next signal transmissionunit SR, and the multiplexer MUX is connected to the output terminalthereof.

Each of the switchable channels CH2 and CH4 further includes a seconddemultiplexer DEMUX2 connected between the DAC and the output buffer SA.

The timing controller 131 outputs the control signal BREN as theinactivation logic value when the pixel data D to be written into thesub-pixels of the focal region FR is received. In this case, in responseto the inactivation logic value of the control signal BREN, themultiplexers MUX and the first demultiplexers DEMUX1 connect adjacentsignal transmission units SR to each other to allow the pixel data D tobe sequentially transmitted to a next signal transmission unit SR. Themultiplexer MUX may transmit the pixel data from the M^(th) signaltransmission unit SR(M) to the (M+1)^(th) signal transmission unitSR(M+1) in response to the inactivation logic value of the controlsignal BREN, and may transmit the pixel data from the M^(th) signaltransmission unit SR(M) to the first demultiplexer DEMUX1 in response tothe activation logic value of the control signal BREN. The firstdemultiplexer DEMUX1 may transmit the pixel data from the (M+1)^(th)signal transmission unit SR(M+1) to the (M+2)^(th) signal transmissionunit SR(M+2) in response to the inactivation logic value of the controlsignal BREN, and may transmit the pixel data from the M^(th) signaltransmission unit SR(M) to the (M+2)^(th) signal transmission unitSR(M+2) in response to the activation logic value of the control signalBREN.

In the channels CH1 to CH4, the sample & holders SH sample data receivedfrom the signal transmission units SR of the shift register and outputthe sampled data simultaneously in synchronization with a clock.

The DAC of each of the pixel data channels CH1 and CH3 converts thepixel data from the sample & holder SH into the data voltage Vdata andoutput it. The data voltage Vdata outputted from the DAC of each of thepixel data channels CH1 and CH3 is applied to the data line 102 throughthe output buffer SA.

The DAC of each of the switchable channels CH2 and CH4 converts thepixel data from the sample & holder SH into the data voltage Vdata andoutput it.

A first input terminal of the second demultiplexer DEMUX2 is connectedto an output terminal of the DAC of the switchable channel CH2, CH4, andthe black grayscale voltage Vblk is applied to a second input terminalof the second demultiplexer DEMUX2. An output terminal of the seconddemultiplexer DEMUX2 is connected to an input terminal of the outputbuffer SA disposed in the switchable channel CH2, CH4. The blackgrayscale voltage Vblk may be generated within the data driver 111 ormay be externally generated and applied to the second demultiplexerDEMUX2.

The second demultiplexer DEMUX2 applies the data voltage Vdata from theDAC to the output buffer SA in response to the inactivation logic valueof the control signal BREN. The second demultiplexer DEMUX2 applies theblack grayscale voltage Vblk to the output buffer SA in response to theactivation logic value of the control signal BREN. As a result, in thefocal region FR, the data voltage Vdata from the DAC of the switchablechannel CH2, CH4 is applied to the data line 102 through the seconddemultiplexer DEMUX2 and the output buffer SA.

When the data driver 111 receives the pixel data of the focal region, itoutputs the data voltage Vdata of the pixel data in all the channels CH1to CH4.

FIG. 21 is a circuit diagram illustrating an operation of the datadriver in a non-focal region, shown in FIGS. 15 and 16 .

Referring to FIG. 21 , the timing controller 131 outputs the controlsignal BREN as the activation logic value when the pixel data D to bewritten into the sub-pixels of the non-focal region NFR is received. Inthis case, in response to the activation logic value of the controlsignal BREN, the multiplexers MUX and the first demultiplexers DEMUX1connect the signal transmission units SR of the pixel data channels CH1and CH3 to each other through a bypass lines passing through the signaltransmission units of the switchable channels CH2 and CH4. Accordingly,when the pixel data of the non-focal region NFR is received by the datadriver 111, the pixel data D is sequentially transmitted only throughthe signal transmission units of the pixel data channels CH1 and CH3 inthe shift register. In this case, the pixel data D is not transmitted tothe signal transmission unit SR, the sample & holder SH, and the DAC inthe switchable channels CH2 and CH4.

In the pixel data channels CH1 and CH3, the sample & holders SH sampledata received from the signal transmission unit SR of the shift registerand output the sampled data simultaneously in synchronization with aclock.

The DAC of each of the pixel data channels CH1 and CH3 converts thepixel data from the sample & holder SH into the data voltage Vdata andoutput it. The data voltage Vdata outputted from the DAC of each of thepixel data channels CH1 and CH3 is applied to the data line 102 throughthe output buffer SA.

In the DAC of each of the switchable channels CH2 and CH4, the seconddemultiplexer DEMUX2 connects the black grayscale voltage Vblk to theinput terminal of the output buffer SA in response to the activationlogic value of the control signal BREN. Accordingly, the black grayscalevoltage Vblk is applied to the data line 102 through the seconddemultiplexer DEMUX2 and the output buffer SA of each of the switchablechannels CH2 and CH4 in the non-focal region.

The objects to be achieved by the present disclosure, the means forachieving the objects, and effects of the present disclosure describedabove do not specify essential features of the claims, and thus, thescope of the claims is not limited to the disclosure of the presentdisclosure.

Although the aspects of the present disclosure have been described inmore detail with reference to the accompanying drawings, the presentdisclosure is not limited thereto and may be embodied in many differentforms without departing from the technical concept of the presentdisclosure. Therefore, the aspects disclosed in the present disclosureare provided for illustrative purposes only and are not intended tolimit the technical concept of the present disclosure. The scope of thetechnical concept of the present disclosure is not limited thereto.Therefore, it should be understood that the above-described aspects areillustrative in all aspects and do not limit the present disclosure. Theprotective scope of the present disclosure should be construed based onthe following claims, and all the technical concepts in the equivalentscope thereof should be construed as falling within the scope of thepresent disclosure.

What is claimed is:
 1. A display device comprising a display panel inwhich a plurality of data lines, a plurality of gate lines, and aplurality of sub-pixels electrically connected to the plurality of datalines and the plurality of gate lines are arranged; and a display driverconfigured to drive the display panel by writing pixel data to thesub-pixels, wherein at least a part of the display panel includes aswitch element configured to electrically connect adjacent sub-pixels toeach other in response to a first logic value of a control signal, andelectrically separate the adjacent sub-pixels from each other inresponse to a second logic value of the control signal, wherein thedisplay driver is configured to apply the second logic value of thecontrol signal to the switch element when receiving pixel data to bewritten to a focal region on the display panel to which a user's gaze isdirected, and applies the first logic value of the control signal to theswitch element when receiving pixel data to be written to a non-focalregion other than the focal region on the display panel.
 2. The displaydevice of claim 1, wherein the pixel data to be written to sub-pixels ofthe focal region includes data having a higher resolution than that ofthe pixel data to be written to sub-pixels of the non-focal region. 3.The display device of claim 2, wherein the display driver is configuredto write pixel data to one of n (n being a positive integer greater thanor equal to 2) sub-pixels adjacent in the non-focal region, and writespreset black grayscale data to the other sub-pixels.
 4. The displaydevice of claim 1, wherein when pixel data of a same grayscale iswritten to sub-pixels of the focal region and the non-focal region,luminance of the non-focal region is lower than luminance of the focalregion.
 5. The display device of claim 1, wherein the non-focal regionis divided into two or more pixel areas having luminance graduallylowered as a distance from the focal region increases.
 6. The displaydevice of claim 1, wherein the display driver includes: a timingcontroller configured to receive the pixel data of the focal region andthe pixel data of the non-focal region, and when receiving the pixeldata of the non-focal region, generate the control signal as the firstlogical value, and when receiving the pixel data of the focal region,generate the control signal as the second logical value; and a datadriver configured to convert the pixel data from the timing controllerinto a data voltage to supply it to the data lines, and supply a blackgrayscale voltage to the data lines.
 7. The display device of claim 6,wherein the timing controller includes an output terminal through whichthe control signal is outputted, and the data driver includes an inputterminal through which the control signal is inputted.
 8. The displaydevice of claim 6, wherein, when receiving the pixel data of thenon-focal region, the timing controller adds black grayscale data tobetween pixel data and transmits it to the data driver.
 9. The displaydevice of claim 8, wherein the data driver is configured to convert theblack grayscale data into the black grayscale voltage and supplies it tothe data lines of the non-focal region.
 10. The display device of claim6, wherein the data driver includes: a plurality of pixel data channelsconfigured to convert pixel data to be written to sub-pixels of thefocal region and the non-focal region into the data voltage and outputit; and a plurality of switchable channels configured, when receivingthe pixel data of the focal region, to convert the pixel data into thedata voltage and output it, and when receiving the pixel data of thenon-focal region, to output the black grayscale voltage.
 11. The displaydevice of claim 10, wherein the data driver further includes a shiftregister including a plurality of signal transmission units configuredto sequentially shift the pixel data received from the timingcontroller, and wherein each of the pixel data channels and theswitchable channels includes: a sample & holder connected to a signaltransmission unit of the shift register; a digital-to-analog converterconfigured to convert the pixel data from the sample & holder into thedata voltage; and an output buffer configured to output the data voltagefrom the digital-to-analog converter to the data line.
 12. The displaydevice of claim 11, wherein the data driver further includes: amultiplexer connected between an M^(th) (M being a positive integer)signal transmission unit and an (M+1)^(th) signal transmission unit; anda first demultiplexer connected between the (M+1)^(th) signaltransmission unit and an (M+2)^(th) signal transmission unit, andwherein each of the switchable channels further includes a seconddemultiplexer connected between the digital-to-analog converter and theoutput buffer.
 13. The display device of claim 12, wherein themultiplexer is configured to transmit pixel data from the M^(th) signaltransmission unit to the (M+1)^(th) signal transmission unit in responseto the second logic value of the control signal, and transmit the pixeldata from the M^(th) signal transmission unit is transferred to thefirst demultiplexer in response to the first logic value of the controlsignal, and wherein the first demultiplexer is configured to transmitthe pixel data from the (M+1)^(th) signal transmission unit to the(M+2)^(th) signal transmission unit in response to the second logicalvalue of the control signal, and transmit the pixel data from the M^(th)signal transmission unit to the (M+2)^(th) signal transmission unit inresponse to the first logic value of the control signal.
 14. The displaydevice of claim 13, wherein the second demultiplexer includes: a firstinput terminal connected to an output terminal of the digital-to-analogconverter; a second input terminal through which the black grayscalevoltage is applied; and an output terminal coupled to the output buffer,wherein the second demultiplexer is configured to apply the data voltagefrom the digital-to-analog converter to the output buffer in response tothe second logic value of the control signal, and apply the blackgrayscale voltage to the output buffer in response to the first logicvalue of the control signal.
 15. A personal immersive system comprising:a system controller configured to lower resolution of an input image ina non-focal region, which is outside a focal region than in the focalregion to which a user's gaze is directed; and a display driverconfigured to write pixel data of the focal region and pixel data of thenon-focal region to pixels of a display panel, supply a black grayscalevoltage to at least some of pixels of the non-focal region on thedisplay panel, and generate a control signal for lowering luminance ofthe non-focal region than luminance of the focal region, wherein atleast a part of a screen of the display panel includes a switch elementconfigured to connect adjacent sub-pixels to each other in response to afirst logic value of the control signal and separate the adjacentsub-pixels from each other in response to a second logical value of thecontrol signal.
 16. The personal immersive system of claim 15, whereinthe display panel includes: a first display panel on which a left-eyeimage having a lower luminance in the non-focal region than in the focalregion is displayed; and a second display panel on which a right-eyeimage having a lower luminance in the non-focal region than in the focalregion is displayed.
 17. A mobile terminal system comprising: a systemcontroller configured to lower resolution of an input image in anon-focal region, which is outside a focal region, than in the focalregion to which a user's gaze is directed; and a display driverconfigured to write pixel data of the focal region and pixel data of thenon-focal region to pixels of a display panel, supply a black grayscalevoltage to at least some of pixels of the non-focal region on thedisplay panel, and generate a control signal for lowering luminance ofthe non-focal region than luminance of the focal region, wherein atleast a part of a screen of the display panel includes a switch elementconfigured to connect adjacent sub-pixels to each other in response to afirst logic value of the control signal and separate the adjacentsub-pixels from each other in response to a second logical value of thecontrol signal.
 18. The mobile terminal system of claim 17, wherein aleft-eye image having a lower luminance in the non-focal region than inthe focal region and a right-eye image having a lower luminance in thenon-focal region than in the focal region are displayed on the displaypanel.